The Mouse models Core will carry out breeding and genotype analysis of mice for evaluation of small-molecule CF therapies and for analysis of small-molecule pharmacology. Wildtype and homozygous CF mice (AF508, G551D, null) with defined genetic background will be generated. The Mouse models Core will also carry out potential difference (PD) measurements, and pharmacokinetic analysis of lead compounds. Wildtype mice will be provided to investigators in nine projects, and various CF mice in five projects. PD measurements (nasal, rectal, ocular) will be used by two projects, and pharmacology studies will be done for seven projects.